טכניון מכון טכנולוגי לישראל
הטכניון מכון טכנולוגי לישראל - בית הספר ללימודי מוסמכים  
M.Sc Thesis
M.Sc StudentBossel Jacob
SubjectWater Waves Propagation on Variable Depth in the Wave
Number Domain and Frequency Domain
DepartmentDepartment of Civil and Environmental Engineering
Supervisor Professor Yehuda Agnon


Abstract

  The following research presents an application of a numerical model for the prediction of two dimensional wave propagation, over an uneven bottom section.   The model is based on the Laplace equation for irrotational flow.  The importance of the research lies in the attempt to predict moving waves over uneven bottom and to predict the interaction between the bottom and the surface wave.  Using a spectral approach enables the prediction of the wave evolution.

  In the first part the linear model was expanded to a nonlinear one, to enable checking energy transfer between the wave frequencies.  The bottom depth was constant.  Using the fast Fourier transform algorithm, which reduces calculation time required in other methods, enabled the calculation of the nonlinear component.  The model refers to a series of waves in a given time and calculates the wave propagation. A second order nonlinear component is added to the linear calculation. 

  Following the model verification a full numerical model of the dealt problem was achieved..  The main purpose of the research was defined as building a model of wave propagating over uneven bottom, in order to investigate the influences of the bottom on energy transformation in the wave spectrum, and decreasing calculation time by a large factor.

  The calculation results were compared to a numerical model, with a satisfactory accuracy, which uses convolution.  The results were also compared to various publications.  After achieving the results, a simulation of the potential values in the time domain was done.  This simulation describes the wave amplitude envelope in the time domain.